Stirring device, bioreactor and culture method for filamentous fungus

Abstract

A stirring device, bioreactor and culture method for a filamentous fungus. A stirring device of the bioreactor comprises an upper stirring paddle, a middle stirring paddle, and a lower stirring paddle which are sequentially arranged in the vertical direction; each upper blade of the upper stirring paddle comprises an arc-shaped first transition portion, an inclined first upper straight section, and a first lower straight section, and an included angle of 60°-80° is formed between the first upper straight section and the first lower straight section; each middle blade of the middle stirring paddle comprises an arc-shaped second transition portion, an inclined second upper straight section, and a second lower straight section, and an included angle of 145°-165° is formed between the second upper straight section and the second lower straight section; each lower blade of the lower stirring paddle comprises an arc-shaped third transition portion, an inclined third upper straight section, and a third lower straight section, and an included angle of 145°-165° is formed between the third upper straight section and the third lower straight section; and the length of the first upper straight section is smaller than that of the first lower straight section, and the length of the third upper straight section is smaller than that of the third lower straight section. The bioreactor allows a high stirring speed without cutting off hyphae.

Description

A stirring device, bioreactor and cultivation method for filamentous fungi Related applications

[0001] This application claims priority to Chinese patent application No. CN 2023117336061 filed on December 18, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of filamentous fungus production and relates to a bioreactor and a culture method for filamentous fungi. Background Art

[0003] Microbial reactors are commonly used for liquid-state fermentation to cultivate microorganisms. A stirring paddle is the primary component in microbial reactors, performing material mixing. Common shapes include vertical or tilted rectangular and crescent-shaped stirring paddles. Conventional stirring paddles are adequate for standard mononuclear cell fermentation. However, for filamentous fungi, particularly those with longer hyphae, such as Rhizopus oryzae shown in Figures 1a and 1b, these conventional stirring paddles present challenges. For example, for a vertical rectangular paddle (the paddle is rectangular as a whole and is set vertically), although the stirring force is strong, due to the sharp edges, during the stirring process, there will be problems of stirring and cutting the mycelium and the paddle getting stuck due to entanglement of the paddle blades; for an inclined rectangular paddle (the paddle is rectangular as a whole and is set at an angle), although an upward or downward stirring force can be generated, the mycelium will be cut; although a crescent-shaped paddle (the shape of the paddle is arc-shaped when viewed from the side or above) can protect the mycelium from being cut, the stirring force is reduced due to the rounded blade surface, which is not conducive to mixing the culture medium and filamentous fungi. Secondly, uneven stirring of filamentous fungi will cause pilling (as shown in Figures 2a and 2b), reducing the contact area between the fungus and the culture medium and reducing growth efficiency. Summary of the Invention

[0004] One aspect of the present disclosure is to design a bioreactor for filamentous fungi, which is suitable for cultivating filamentous fungi and allows a higher stirring speed without cutting the mycelium, so that the mycelium can evenly contact the culture medium, thereby improving the growth efficiency of the filamentous fungi.

[0005] Another aspect of the present disclosure relates to a method for cultivating filamentous fungi, which allows a higher stirring speed without cutting the mycelium, so that the mycelium contacts the culture medium evenly, thereby improving the growth efficiency of the filamentous fungi.

[0006] A first aspect of the present disclosure provides a bioreactor for filamentous fungi, comprising a fermenter and a stirring device disposed in the fermenter, wherein the stirring device comprises an upper stirring paddle, a middle stirring paddle, and a lower stirring paddle disposed sequentially from top to bottom;

[0007] The upper stirring paddle includes a plurality of upper blades, each of the upper blades having an arc-shaped first transition section, a first upper straight section extending upward and obliquely from the first transition section, and a first lower straight section extending downward and obliquely from the first transition section, wherein a first angle is formed between the first upper straight section and the first lower straight section, and the first angle is 60° to 80°;

[0008] The middle stirring paddle includes a plurality of middle blades, each of the middle blades having an arc-shaped second transition section, a second upper straight section extending upward and obliquely from the second transition section, and a second lower straight section extending downward and obliquely from the second transition section, wherein a second angle is formed between the second upper straight section and the second lower straight section, and the second angle is 145° to 165°;

[0009] The lower stirring paddle includes a plurality of lower blades, each of the lower blades having an arc-shaped third transition section, a third upper straight section extending upward and obliquely from the third transition section, and a third lower straight section extending downward and obliquely from the third transition section, wherein a third angle is formed between the third upper straight section and the third lower straight section, and the third angle is 145° to 165°;

[0010] Specifically, the lengths of the first upper straight section, the second upper straight section and the third upper straight section extending obliquely upward are L11, L21 and L31 respectively, and the lengths of the first lower straight section, the second lower straight section and the third lower straight section extending obliquely downward are L12, L22 and L32 respectively, L11<L12, L31>L32, and L11<L21<L31, L12>L22>L32.

[0011] In some embodiments, the inclination angle between the first upper straight section and the horizontal plane is equal to the inclination angle between the first lower straight section and the horizontal plane.

[0012] In some embodiments, the inclination angle between the second upper straight section and the horizontal plane is equal to the inclination angle between the second lower straight section and the horizontal plane.

[0013] In some embodiments, the inclination angle between the third upper straight section and the horizontal plane is equal to the inclination angle between the third lower straight section and the horizontal plane.

[0014] In some embodiments, the first transition section, the second transition section and the third transition section are respectively composed of a circular arc, the central angle of the circular arc corresponding to the first transition section is 60°~80°, the central angle of the circular arc corresponding to the second transition section is 145°~165°, and the central angle of the circular arc corresponding to the third transition section is 145°~165°.

[0015] In some embodiments, the first transition section of each upper blade is connected to the stirring shaft, the second transition section of each middle blade is connected to the stirring shaft, and the third transition section of each lower blade is connected to the stirring shaft; the plurality of upper blades, the plurality of middle blades and the plurality of lower blades are evenly arranged along the circumferential direction of the stirring shaft.

[0016] In some embodiments, the number and position of the plurality of upper blades, the plurality of middle blades and the plurality of lower blades correspond one to one, and each of the upper blades, one of the middle blades and one of the lower blades are aligned with each other in the up and down directions.

[0017] In some embodiments, the number of the upper blades, the middle blades, and the lower blades is equal, and ranges from 3 to 10 respectively.

[0018] In some embodiments, in a top view, each of the upper blades, each of the middle blades, and each of the lower blades extend along a diameter direction of the fermentation tank.

[0019] In some embodiments, L11 is less than half of L12, L21 and L22 are equal, and L32 is less than half of L31.

[0020] In some embodiments, the fermentation scale of the fermenter is 5-10 L, and the stirring speed of the stirring device is 850-1100 rpm; more preferably 900-1000 rpm.

[0021] Another aspect of the present disclosure provides a stirring device for filamentous fungi, which is used to be arranged in a fermentation tank, including an upper stirring paddle, a middle stirring paddle and a lower stirring paddle arranged in sequence from top to bottom;

[0022] The upper stirring paddle includes a plurality of upper blades, each of the upper blades having an arc-shaped first transition section, a first upper straight section extending upward and obliquely from the first transition section, and a first lower straight section extending downward and obliquely from the first transition section, wherein a first angle is formed between the first upper straight section and the first lower straight section, and the first angle is 60° to 80°;

[0023] The middle stirring paddle includes a plurality of middle blades, each of the middle blades having an arc-shaped second transition section, a second upper straight section extending upward and obliquely from the second transition section, and a second lower straight section extending downward and obliquely from the second transition section, wherein a second angle is formed between the second upper straight section and the second lower straight section, and the second angle is 145° to 165°;

[0024] The lower stirring paddle includes multiple lower blades, each of the lower blades has an arc-shaped third transition section, a third upper straight section extending upward and obliquely from the third transition section, and a third lower straight section extending downward and obliquely from the third transition section, a third angle is formed between the third upper straight section and the third lower straight section, and the third angle is 145°~165°.

[0025] In some embodiments, the lengths of the first upper straight section, the second upper straight section, and the third upper straight section extending obliquely upward are L11, L21, and L31, respectively; the lengths of the first lower straight section, the second lower straight section, and the third lower straight section extending obliquely downward are L12, L22, and L32, respectively, L11<L12, L31>L32, and L11<L21<L31, L12>L22>L32.

[0026] In some embodiments, the inclination angle between the first upper straight section and the horizontal plane is equal to the inclination angle between the first lower straight section and the horizontal plane; the inclination angle between the second upper straight section and the horizontal plane is equal to the inclination angle between the second lower straight section and the horizontal plane; the inclination angle between the third upper straight section and the horizontal plane is equal to the inclination angle between the third lower straight section and the horizontal plane.

[0027] In some embodiments, in a top view, each of the upper blades, each of the middle blades, and each of the lower blades extend along a diameter direction of the fermentation tank.

[0028] In some embodiments, the stirring speed of the stirring device is 850-1100 rpm.

[0029] Another aspect of the present disclosure provides a method for culturing filamentous fungi, comprising the following steps: adding strains of filamentous fungi and a culture medium into the bioreactor, turning on a stirring device to mix the strains and the culture medium, and culturing.

[0030] In some embodiments, the fermentation scale in the fermenter is controlled to be 5-10 L, and the stirring speed of the stirring device is controlled to be 850-1100 rpm.

[0031] The bioreactor and stirring device disclosed herein, through the mutual cooperation of three specially shaped stirring paddles, have a relatively rounded transition section that reduces the possibility of filamentous fungi getting stuck in the paddles, and the possibility of mycelium being cut is extremely low; at the same time, the upper straight section extending upward and the lower straight section extending downward can provide higher stirring force, especially the synergistic effect of the special shapes of the upper, middle and lower blades, which can disperse the liquid well and allow a higher stirring speed (up to 850 rpm or more), so that the mycelium is evenly contacted with the culture medium, thereby improving the growth efficiency and yield of filamentous fungi. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0033] FIG1a and FIG1b are magnified microscope photographs of Rhizopus oryzae.

[0034] Figures 2a and 2b are photos of the pilling phenomenon that occurs during the cultivation of filamentous fungi.

[0035] FIG3 is a schematic diagram of a bioreactor according to an embodiment of the present disclosure.

[0036] FIG4 is a schematic diagram of a combination of three stirring paddles according to an embodiment of the present disclosure.

[0037] FIG5 is a top view of three stirring paddle combinations according to an embodiment of the present disclosure.

[0038] FIG6 is a perspective view of an upper stirring paddle according to an embodiment of the present disclosure.

[0039] FIG7 is a perspective view of a middle stirring paddle according to an embodiment of the present disclosure.

[0040] FIG8 is a perspective view of a lower stirring paddle according to an embodiment of the present disclosure.

[0041] FIG9 is a structural diagram of an upper blade according to an embodiment of the present disclosure.

[0042] FIG10 is a structural diagram of a middle blade according to an embodiment of the present disclosure.

[0043] FIG11 is a structural diagram of a lower blade according to an embodiment of the present disclosure.

[0044] 12a and 12b are fluid dynamic models of a bioreactor according to an embodiment of the present disclosure; FIG12c shows a photograph of a fermenter of a simulation embodiment.

[0045] 13 to 18 show six views of an upper stirring paddle according to an embodiment of the present disclosure.

[0046] 18 to 24 show six views of a middle stirring paddle according to an embodiment of the present disclosure.

[0047] 25 to 30 show six views of a lower stirring paddle according to an embodiment of the present disclosure.

[0048] Of which: 100 - fermentation tank; 200 - stirring device;

[0049] 1 - upper stirring paddle; 10 - upper blade; 11 - first upper straight section; 12 - first lower straight section; 13 - first transition section; 14 - first hub;

[0050] 2 - middle stirring paddle; 20 - middle blade; 21 - second upper straight section; 22 - second lower straight section; 23 - second transition section; 24 - second hub;

[0051] 3 - lower stirring paddle; 30 - lower blade; 31 - third upper straight section; 32 - third lower straight section; 33 - third transition section; 34 - third hub;

[0052] 4 - Stirring shaft. DETAILED DESCRIPTION

[0053] The following is a detailed description of the preferred embodiments of the present disclosure to make the advantages and features of the present disclosure more easily understood by those skilled in the art. It should be noted that the description of these embodiments is used to help understand the present disclosure, but does not constitute a limitation of the present disclosure.

[0054] The present embodiment provides a stirring device and a bioreactor suitable for filamentous fungi, which are suitable for cultivating filamentous fungi. Filamentous fungi include but are not limited to fungi in the genera Chytridiomycetes, Achyranthes, Rhizopus, Trichoderma, Aspergillus and Mucor, such as Rhizopus oryzae. Referring to Figure 3, the bioreactor for filamentous fungi includes a fermentation tank 100 and a stirring device 200 arranged in the fermentation tank 100, and the stirring device 200 includes an upper stirring paddle 1, a middle stirring paddle 2 and a lower stirring paddle 3 arranged in sequence from top to bottom. The upper stirring paddle 1, the middle stirring paddle 2 and the lower stirring paddle 3 are arranged on the stirring shaft 4 at intervals from top to bottom, and the axis of the stirring shaft 4 extends in the up and down direction. The upper end of the stirring shaft 4 is connected to the driving device M. After the driving device M is started, the stirring shaft 4 rotates around its own axis, thereby driving the upper stirring paddle 1, the middle stirring paddle 2 and the lower stirring paddle 3 to rotate synchronously. The driving device M includes a motor.

[0055] As shown in Figures 4 to 8 , the upper stirring paddle 1 includes a plurality of upper blades 10, the middle stirring paddle 2 includes a plurality of middle blades 20, and the lower stirring paddle 3 includes a plurality of lower blades 30. The number and position of the plurality of upper blades 10, the plurality of middle blades 20, and the plurality of lower blades 30 correspond to each other, and each upper blade 10, a middle blade 20, and a lower blade 30 are aligned vertically. From a top-down perspective as shown in Figure 5 , each upper blade 10, each middle blade 20, and each lower blade 30 extends along the diameter of the fermenter 100; that is, each upper blade 10, middle blade 20, or lower blade 30 is not bent or curved in the diameter direction of the stirring shaft 4. Furthermore, the number of upper blades 10, middle blades 20, and lower blades 30 is equal, ranging from 3 to 10 respectively. Specifically, in this embodiment, the number of upper blades 10, middle blades 20, and lower blades 30 is six.

[0056] FIG9 illustrates the structure of the upper blades 10 as viewed along the diameter of the stirring shaft 4. As shown in FIG9 and FIG13 to FIG20 , each upper blade 10 includes an arcuate first transition section 13, a first upper straight section 11 extending upward and obliquely from the first transition section 13, and a first lower straight section 12 extending downward and obliquely from the first transition section 13. A first angle is formed between the first upper straight section 11 and the first lower straight section 12. The first angle is in the range of 60° to 80°, preferably 65° to 75°, and specifically 73° in this embodiment.

[0057] Furthermore, the first upper straight section 11 and the first lower straight section 12 are each shaped like an inclined flat plate, and the first transition section 13 is shaped like an arc. The contour of the first transition section 13 can be formed by one or more circular arcs. In this embodiment, the contour of the first transition section 13 is formed by one circular arc with equal curvature at all locations. The first included angle described above is the central angle corresponding to the first transition section 13.

[0058] The length of first upper straight section 11 is denoted as L11, and the length of first lower straight section 12 is denoted as L12. L11 < L12, meaning that the length of first upper straight section 11 is less than the length of first lower straight section 12. Furthermore, L11 is less than half of L12 to provide a greater downward stirring force. The inclination angle between first upper straight section 11 and the horizontal plane is equal to the inclination angle between first lower straight section 12 and the horizontal plane.

[0059] Figure 10 shows the structure of the middle blades 20 as viewed along the diameter of the agitator shaft 4. As shown in Figures 10 and 20 to 26, each middle blade 20 comprises an arcuate second transition section 23, a second upper straight section 21 extending upward and obliquely from the second transition section 23, and a second lower straight section 22 extending downward and obliquely from the second transition section 23. The second upper straight section 21 and the second lower straight section 22 form a second angle, which is between 145° and 165°, preferably between 145° and 155°, and specifically 148° in this embodiment. Furthermore, the second upper straight section 21 and the second lower straight section 22 are each inclined flat, and the second transition section 23 is an arcuate plate. The contour of the second transition section 23 can be formed by one or more circular arcs. In this embodiment, the contour of the second transition section 23 is formed by one circular arc with equal curvature at all locations. The aforementioned second angle is the central angle of the second transition section 23.

[0060] The length of the second upper straight section 21 is denoted as L21, and the length of the second lower straight section 22 is denoted as L22. L21 = L22, meaning that the length of the second upper straight section 21 is equal to the length of the second lower straight section 22. The inclination angle between the second upper straight section 21 and the horizontal plane is equal to the inclination angle between the second lower straight section 22 and the horizontal plane. Furthermore, the middle blade 20 is mirror-symmetrical from top to bottom.

[0061] Figure 11 shows the structure of the lower blades 30 as viewed along the diameter of the agitator shaft 4. As shown in Figure 11 and Figures 27 to 32, each lower blade 30 comprises an arcuate third transition section 33, a third upper straight section 31 extending upward and obliquely from the third transition section 33, and a third lower straight section 32 extending downward and obliquely from the third transition section 33. A third angle is formed between the third upper straight section 31 and the third lower straight section 32. The third angle is in the range of 145° to 165°, preferably 145° to 155°, and specifically 148° in this embodiment. Furthermore, the third upper straight section 31 and the third lower straight section 32 are each in the shape of an inclined flat plate, while the third transition section 33 is in the shape of an arc. The contour of the third transition section 33 can be formed by one or more circular arcs. In this embodiment, the contour of the third transition section 33 is formed by one circular arc with equal curvature at all locations. The aforementioned third angle is the central angle of the third transition section 33.

[0062] The length of the third upper straight section 31 is denoted as L31, and the length of the third lower straight section 32 is denoted as L32. L31>L32, meaning that the length of the third upper straight section 31 is greater than the length of the third lower straight section 32. Furthermore, L32 is less than half of L31 to provide a greater upward stirring force. The inclination angle between the third upper straight section 31 and the horizontal plane is equal to the inclination angle between the third lower straight section 32 and the horizontal plane.

[0063] Furthermore, L11<L21<L31, L12>L22>L32. That is, the length of the first upper straight segment 11 is less than the length of the second upper straight segment 21, which is less than the length of the third upper straight segment 31; the length of the first lower straight segment 12 is greater than the length of the second lower straight segment 22, which is greater than the length of the third lower straight segment 32.

[0064] It should also be noted that the bending directions of the upper blades 10, middle blades 20, and lower blades 30 are consistent. Taking the uppermost blade in the top view shown in FIG5 as an example, the first upper straight section 11 and the first lower straight section 12 of the upper blade 10 extend obliquely to the left relative to the first transition section 13. The second upper straight section 21 and the second lower straight section 22 of the corresponding middle blade 20 also extend obliquely to the left relative to the second transition section 23. The third upper straight section 31 and the third lower straight section 32 of the corresponding lower blade 30 also extend to the left relative to the third transition section 33. Each blade is integrally formed and is curved and rounded at the transition section, forming two straight sections and one transition section.

[0065] The first transition section 13 of each upper blade 10 is connected to the stirring shaft 4, the second transition section 23 of each middle blade 20 is connected to the stirring shaft 4, and the third transition section 33 of each lower blade 30 is connected to the stirring shaft 4. The plurality of upper blades 10, the plurality of middle blades 20 and the plurality of lower blades 30 are evenly arranged along the circumferential direction of the stirring shaft 4. Further, as shown in Figure 6, the upper stirring paddle 1 has a first hub 14, which is concentrically mounted on the stirring shaft 4, and the first transition section 13 of each upper blade 10 is fixedly connected to or integrally arranged with the stirring shaft 4. As shown in Figure 7, the middle stirring paddle 2 has a second hub 24, which is concentrically mounted on the stirring shaft 4, and the second transition section 23 of each middle blade 20 is fixedly connected to or integrally arranged with the stirring shaft 4. As shown in Figure 8, the lower stirring paddle 3 has a third hub 34, which is concentrically mounted on the stirring shaft 4, and the third transition section 33 of each lower blade 30 is fixedly connected to or integrally arranged with the stirring shaft 4.

[0066] The volume of the fermentation tank 100 is 7-15 L, the fermentation scale (specifically, the volume of the fermentation system in the fermentation tank 100) is 5-10 L, and the stirring speed of the stirring device 200 is 850-1100 rpm, preferably 900-1000 rpm.

[0067] This embodiment also provides a method for cultivating filamentous fungi, comprising the following steps: adding strains of filamentous fungi and culture medium into a bioreactor, turning on a stirring device to mix the strains and culture medium, and cultivating.

[0068] Furthermore, the fermentation scale in the fermenter 100 is controlled to be 5-10 L, and the stirring speed of the stirring device 200 is controlled to be 850-1100 rpm, preferably 900-1000 rpm.

[0069] A simulated flow dynamics model was constructed for the bioreactor of this example, with Figures 12a and 12b showing two different angles. This simulation demonstrates that the new paddle shape can generate the same horizontal and vertical stirring forces as a rectangular blade, but with a more gentle shape. This effectively disperses the liquid within the tank, mimicking the flow and diffusion direction comparable to a rectangular blade, ensuring uniform contact between the mycelium and the culture medium, improving growth efficiency. Application Examples

[0070] Liquid culture medium was added to the fermentation tank 100, and Rhizopus oryzae was inoculated (the initial spore count was about 1*10 7 ), the stirring device 200 is turned on at a speed of 900 rpm, and the culture is carried out at 25 to 30° C. After 20 hours, a large amount of hyphae can be observed in the fermentation tank 100 with the naked eye, as shown in FIG12c .

[0071] Microscopic observation of the cultivated filamentous fungi at a stirring rate of 900 rpm in the bioreactor of this embodiment showed that their hyphae remained relatively intact and free of clumping. However, if the blades were replaced with conventional vertical rectangular paddles, the stirring rate would only reach 300-500 rpm, and the fungal hyphae would often break.

[0072] In this bioreactor, three blades of different shapes are combined and cooperate with each other, which reduces the possibility of filamentous fungi getting stuck in the paddle and the possibility of mycelium being cut is extremely low. At the same time, the straight angles can make up for the stirring force, so that the stirring force lacking in this shape can be compensated by slightly increasing the stirring speed. The stirring rate can reach more than 900rpm, greatly improving the production efficiency of filamentous fungi.

[0073] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. In the event of any conflict or inconsistency between the definitions used herein and those in other published documents, the definitions used herein shall prevail.

[0075] Unless the context clearly indicates otherwise, the indefinite articles "a," "an," and "an" preceding an element or component herein are intended to specify the number of instances (i.e., the number of occurrences) of the element or component without limitation. Thus, "a," "an," and "an" should be understood to include one or at least one, and the singular form of an element or component also includes the plural form. It is further understood that in this disclosure, "a plurality" refers to two or more, and other quantifiers are similar.

[0076] The above embodiment is only for illustrating the technical concept and features of the present disclosure and is a preferred embodiment. Its purpose is to enable people familiar with this technology to understand the content of the present disclosure and implement it accordingly, and it cannot be used to limit the scope of protection of the present disclosure.

Claims

1. A bioreactor for filamentous fungi, comprising: Fermentation tanks; and A stirring device is arranged in the fermentation tank and comprises an upper stirring paddle, a middle stirring paddle and a lower stirring paddle arranged in sequence from top to bottom; Wherein, the upper stirring paddle comprises a plurality of upper blades, each of the upper blades comprises an arc-shaped first transition section, a first upper straight section extending upward and obliquely from the first transition section, and a first lower straight section extending downward and obliquely from the first transition section, a first angle is formed between the first upper straight section and the first lower straight section, and the first angle is 60° to 80°; The middle stirring paddle comprises a plurality of middle blades, each of the middle blades comprises an arc-shaped second transition section, a second upper straight section extending upward and obliquely from the second transition section, and a second lower straight section extending downward and obliquely from the second transition section, a second angle is formed between the second upper straight section and the second lower straight section, and the second angle is 145° to 165°; The lower stirring paddle comprises a plurality of lower blades, each of the lower blades comprises an arc-shaped third transition section, a third upper straight section extending upward and obliquely from the third transition section, and a third lower straight section extending downward and obliquely from the third transition section, a third angle is formed between the third upper straight section and the third lower straight section, and the third angle is 145° to 165°; The lengths of the first upper straight section, the second upper straight section and the third upper straight section extending obliquely upward are L11, L21 and L31 respectively, and the lengths of the first lower straight section, the second lower straight section and the third lower straight section extending obliquely downward are L12, L22 and L32 respectively, L11<L12, L31>L32, and L11<L21<L31, L12>L22>L32.

2. The bioreactor for filamentous fungi according to claim 1, characterized in that The inclination angle between the first upper straight section and the horizontal plane is equal to the inclination angle between the first lower straight section and the horizontal plane.

3. A bioreactor for filamentous fungi according to any preceding claim, characterised in that The inclination angle between the second upper straight section and the horizontal plane is equal to the inclination angle between the second lower straight section and the horizontal plane.

4. A bioreactor for filamentous fungi according to any preceding claim, characterised in that The inclination angle between the third upper straight section and the horizontal plane is equal to the inclination angle between the third lower straight section and the horizontal plane.

5. A bioreactor for filamentous fungi according to any preceding claim, characterised in that The first transition section, the second transition section and the third transition section are respectively composed of a circular arc, the central angle of the circular arc corresponding to the first transition section is 60°~80°, the central angle of the circular arc corresponding to the second transition section is 145°~165°, and the central angle of the circular arc corresponding to the third transition section is 145°~165°.

6. A bioreactor for filamentous fungi according to any preceding claim, characterised in that The first transition section of each of the upper blades is connected to the stirring shaft, the second transition section of each of the middle blades is connected to the stirring shaft, and the third transition section of each of the lower blades is connected to the stirring shaft; The plurality of upper blades, the plurality of middle blades and the plurality of lower blades are respectively evenly arranged along the circumferential direction of the stirring shaft.

7. The bioreactor for filamentous fungi according to claim 6, characterized in that The number and positions of the plurality of upper blades, the plurality of middle blades and the plurality of lower blades correspond to each other one by one, and each of the upper blades, one of the middle blades and one of the lower blades are aligned with each other in the up-down direction.

8. A bioreactor for filamentous fungi according to any preceding claim, characterised in that The number of the upper blades, the middle blades and the lower blades is equal, and is 3 to 10 respectively.

9. A bioreactor for filamentous fungi according to any preceding claim, characterised in that In a top view, each of the upper blades, each of the middle blades and each of the lower blades respectively extends along the diameter direction of the fermentation tank.

10. A bioreactor for filamentous fungi according to any preceding claim, characterised in that L11 is less than half of L12, L21 and L22 are equal, and L32 is less than half of L31.

11. The bioreactor for filamentous fungi according to any one of claims 1 to 10, characterized in that: The fermentation scale of the fermenter is 5-10 L, and the stirring speed of the stirring device is 850-1100 rpm.

12. A stirring device for filamentous fungi, which is used to be arranged in a fermentation tank, comprising an upper stirring paddle, a middle stirring paddle and a lower stirring paddle arranged in sequence from top to bottom; in, The upper stirring paddle comprises a plurality of upper blades, each of the upper blades comprises an arc-shaped first transition section, a first upper straight section extending upward and obliquely from the first transition section, and a first lower straight section extending downward and obliquely from the first transition section, a first angle is formed between the first upper straight section and the first lower straight section, and the first angle is 60° to 80°; The middle stirring paddle comprises a plurality of middle blades, each of the middle blades comprises an arc-shaped second transition section, a second upper straight section extending upward and obliquely from the second transition section, and a second lower straight section extending downward and obliquely from the second transition section, a second angle is formed between the second upper straight section and the second lower straight section, and the second angle is 145° to 165°; The lower stirring paddle includes a plurality of lower blades, each of the lower blades having an arc-shaped third transition section, a third upper straight section extending upward and obliquely from the third transition section, and a third lower straight section extending downward and obliquely from the third transition section, a third angle being formed between the third upper straight section and the third lower straight section, and the third angle being 145° to 165°.

13. The stirring device according to claim 12, characterized in that: The lengths of the first upper straight section, the second upper straight section and the third upper straight section extending obliquely upward are L11, L21 and L31 respectively, and the lengths of the first lower straight section, the second lower straight section and the third lower straight section extending obliquely downward are L12, L22 and L32 respectively, L11<L12, L31>L32, and L11<L21<L31, L12>L22>L32.

14. The stirring device according to claim 12 or 13, characterized in that: The inclination angle between the first upper straight section and the horizontal plane is equal to the inclination angle between the first lower straight section and the horizontal plane; the inclination angle between the second upper straight section and the horizontal plane is equal to the inclination angle between the second lower straight section and the horizontal plane; the inclination angle between the third upper straight section and the horizontal plane is equal to the inclination angle between the third lower straight section and the horizontal plane.

15. A stirring device according to any preceding claim, characterised in that In a top view, each of the upper blades, each of the middle blades and each of the lower blades respectively extends along the diameter direction of the fermentation tank.

16. A stirring device according to any preceding claim, characterised in that The stirring speed of the stirring device is 850-1100 rpm.

17. A method for culturing filamentous fungi, characterized in that: The method comprises the following steps: putting strains of filamentous fungi and culture medium into the bioreactor according to any one of claims 1 to 11, turning on a stirring device to mix the strains and culture medium, and culturing.

18. The method for culturing filamentous fungi according to claim 17, characterized in that: The fermentation scale in the fermenter is controlled to be 5-10 L, and the stirring speed of the stirring device is controlled to be 850-1100 rpm.

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